Jupyter上でのforループのスコープ

Jupyter上でのforループのスコープ.ipynb

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      "source": "# Jupyter上でのforループのスコープ\n\n結論: `global` を付けなくても「期待」通りの結果が得られるが, forループをマクロの中に入れてしまうと通用しなくなるので, 函数外では `global` を付けて書くべきであることを知っておいた方がよい."
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      "source": "n = 10^7\nc = 0\nfor i in 1:n\n    c += ifelse(rand()^2 + rand()^2 < 1, 1, 0)\nend\n4c/n",
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      "source": "n = 10^7\nc = 0\n@time for i in 1:n\n    c += ifelse(rand()^2 + rand()^2 < 1, 1, 0)\nend\n4c/n",
      "execution_count": 2,
      "outputs": [
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          "ename": "UndefVarError",
          "evalue": "UndefVarError: c not defined",
          "traceback": [
            "UndefVarError: c not defined",
            "",
            "Stacktrace:",
            " [1] macro expansion at .\\In[2]:4 [inlined]",
            " [2] macro expansion at .\\util.jl:156 [inlined]",
            " [3] top-level scope at .\\In[2]:3 [inlined]",
            " [4] top-level scope at .\\none:0"
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      "cell_type": "code",
      "source": "n = 10^7\nc = 0\nfor i in 1:n\n    global c += ifelse(rand()^2 + rand()^2 < 1, 1, 0)\nend\n4c/n",
      "execution_count": 3,
      "outputs": [
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      "cell_type": "code",
      "source": "n = 10^7\nc = 0\n@time for i in 1:n\n    global c += ifelse(rand()^2 + rand()^2 < 1, 1, 0)\nend\n4c/n",
      "execution_count": 4,
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          "text": "  1.245922 seconds (40.00 M allocations: 762.914 MiB, 3.81% gc time)\n",
          "name": "stdout"
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          "execution_count": 4,
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      "cell_type": "code",
      "source": "function pi_MonteCarlo(n=10^7)\n    c = 0\n    for i in 1:n\n        c += ifelse(rand()^2 + rand()^2 < 1, 1, 0)\n    end\n    4c/n\nend\npi_MonteCarlo(1);",
      "execution_count": 5,
      "outputs": []
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      "cell_type": "code",
      "source": "@time pi_MonteCarlo()",
      "execution_count": 6,
      "outputs": [
        {
          "output_type": "stream",
          "text": "  0.081078 seconds (35.84 k allocations: 1.959 MiB)\n",
          "name": "stdout"
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          "output_type": "execute_result",
          "execution_count": 6,
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    {
      "metadata": {
        "trusted": true
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      "cell_type": "code",
      "source": "@time pi_MonteCarlo(10^9)",
      "execution_count": 7,
      "outputs": [
        {
          "output_type": "stream",
          "text": "  3.555929 seconds (6 allocations: 192 bytes)\n",
          "name": "stdout"
        },
        {
          "output_type": "execute_result",
          "execution_count": 7,
          "data": {
            "text/plain": "3.141561348"
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